Injection of impurities into microelectronic (e.g., semiconductor) devices is often significant since it typically impacts a number of factors relating to the electrical function of the device, production yield, quality, and the like. Subsequent to impurity injection, the formation of device elements typically involves the use of deposited films or insulating films in connection with circuit distribution. In general, the manufacture of microelectronic devices often involves a number of steps including photolithographic process steps for transferring a mask having a predetermined pattern onto a wafer surface, oxidation process steps, impurity doping process steps, metallization process steps, and related process steps.
As a result of these processes, contaminants often accumulate on the devices. As an example, the devices may be sensitive to extremely low levels of contaminants such as those present on the order of 12 parts per million. Additionally, patterns in the devices may be adversely effected by the contaminants, such as those which are 12 micrometers or less in diameter. Thus close monitoring of the processes involved in manufacturing the devices may be desirable.
Wafer cleaning processes typically serve an important role in controlling contaminant levels in microelectronic devices. Device cleaning is often required after various individual processes are carried out such as, for example, oxidation, photolithography, diffusion, ion injection, epitaxial film formation using a CVD (Chemical Vapor Deposition) method, metallic processes, and the like. Conventional cleaning processes typically fall into two categories: chemical methods and physical methods. Chemical methods usually encompass using deionized water, acid or alkali etching, oxidation/reduction using corresponding agents, plasma carbonization of organic material, decomposition using organic cleaners, and the like. Physical methods typically encompass utilizing organic cleaners or ultrasonic waves on the wafers, grinding the wafers to attempt to remove particles which may be present on the wafers, brushing the wafers to potentially remove any deposited particles, and spraying the wafers with a high pressure medium such as deionized water, gas, or the like. These techniques are known to one who is skilled in the art.
A common method used in cleaning of microelectronic devices typically involves removing impurities on a wafer surface using a standard cleaning solution, rinsing the wafer using deionized water, contacting the wafer surface with a dilute hydrogen fluoride solution to remove oxidation films and metallic contaminants, rerinsing the wafer using deionized water, and finally spin drying the wafer. A standard solution usually contains a mixture of ammonium hydroxide, hydrogen peroxide, and deionized water which is intended to clean and remove: (1) inorganic contaminants such as dust, (2) organic components, and (3) thin oxidized films which may be present on the wafer surface. Other contaminants such as metallic contaminants can be removed from the wafer surface using dilute hydrogen fluoride.
The above cleaning method suffers from potential drawbacks. Specifically, it may be difficult to completely remove contaminants of elements having high oxidation numbers, such as copper for example, along with organic contaminants by only using the cleaning solution by itself. Moreover, erosion of the wafer surface may occur as a result of this cleaning method, with the surface having an undesirable .mu.-roughness.
There is a need in the art for cleaning compositions and methods of using the same which potentially remove organic contaminants, along with metallic contaminants having a higher oxidation-reduction potential than hydrogen. It would be particularly desirable if the cleaning compositions resulted in minimal wafer surface erosion when contacted by the compositions. These contaminants include certain contaminants more efficiently than current methods.